Metabolic dysfunction-associated fatty liver disease is associated with increased all-cause mortality in the United States

Background & Aims: Recently, international experts proposed redefining non-alcoholic fatty liver disease (NAFLD) as metabolic dysfunction-associated fatty liver disease (MAFLD), based on modified criteria. It is suspected that outcomes such as mortality may differ for these clinical entities. We studied the impact of MAFLD and NAFLD on all-cause and cause-specific mortality in US adults. Methods: We analyzed data from 7,761 participants in the Third National Health and Nutrition Examination Survey and their linked mortality through 2015. NAFLD was diagnosed by ultrasonographic evidence of hepatic steatosis without other known liver diseases. MAFLD was defined based on the criteria proposed by an international expert panel. The Cox proportional hazard model was used to study all-cause mortality and cause-specific mortality between MAFLD and NAFLD, with adjustments for known risk factors. Results: During a median follow-up of 23 years, individuals with MAFLD had a 17% higher risk of all-cause mortality (hazard ratio [HR] 1.17; 95% CI 1.04-1.32). Furthermore, MAFLD was associated with a higher risk of cardiovascular mortality. NAFLD per se did not increase the risk of all-cause mortality. Individuals who met both definitions had a higher risk of all-cause mortality (HR 1.13, 95% CI 1.00-1.26), while individuals who met the definition for MAFLD but not NAFLD had a 1.7-fold higher risk of all-cause mortality (HR 1.66, 95% CI 1.19-2.32). Estimates for all-cause mortality were higher for those with advanced fibrosis and MAFLD than for those with advanced fibrosis and NAFLD. Conclusions: In this US population-based study, MAFLD was associated with an increased risk of all-cause mortality, while NAFLD demonstrated no association with all-cause mortality after adjusting for metabolic risk factors. Lay summary: Our findings provide further support for the idea that non-alcoholic fatty liver disease (NAFLD) is a part of a broader multi-system disease that also includes obesity, diabetes, high blood pressure, and high cholesterol. Therefore, re-defining NAFLD as metabolic dysfunction-associated fatty liver disease (MAFLD) may help improve our understanding of predictors that increase the risk of death.